In a fuel injection system, the fuel is conveyed by means of pipes connected on the interfaces comprising pumps, rails and injectors. Thus, a high-pressure pump distributes the fuel to a common rail by means of a pipe connecting the pump to the rail. The fuel is then transported towards the injectors by pipes which connect the rail to the injectors.
Each end of a pipe is formed by a connector which is generally spherical in shape which allows a slight inclination of the pipe, said pipe being screwed and tightened on the interface in order to fix the position held by the pipe and to produce a sealing effect in this region.
However, it is always possible for fuel leaks to occur at each connection: devices for collecting these accidental leaks, to channel them and direct them towards a low-pressure circuit have already been proposed.
Thus, FR-2878935A describes a protection device suitable for a pressurized fuel feed pipe connection, especially a high-pressure pipe of a fuel injection pump for an internal combustion engine of a motor vehicle. This device comprises two protection elements delimiting an enclosed area for confining fuel leaks from the connection, and an evacuation orifice which is made in the region of these protection elements and is capable of allowing fuel to flow outside.
The main disadvantage of a prior art device of this type is, on the one hand, its size and, on the other hand, the risk of leaks occurring in the region of the joining plane of the two protection elements.
The same type of collection devices are described in documents DE-20314164 and U.S. Pat. No. 5,185,144.
Likewise, a known device for collecting leaks is described in GB-1,212,818-A, but this device is unable to recover leaks in the region of the connection between the feed pipe and the injector.
Finally, document WO-03/087567-A relates to an injector comprising a leak connection for the injection of fuel into the combustion chamber of an internal combustion engine, the leak connection being produced from a single piece with an injector element and comprising a leak connection sleeve which is formed integrally to connect a leak return conduit. A recess is formed in the injector in a transition location between a leak bore in the leak connection and a leak admission bore in the injector, and the recess is configured as a groove which completely surrounds the injector.
The leak connection is mounted on the injector: it is thus mounted in a rigid manner on the injector and allows permanent leaks to be collected. Furthermore, it is necessary to produce a groove in the internal wall of the injector. Thus, an assembly of this type does not allow any degree of freedom between the injector and the feed pipe. In addition, the sealing effect between the leak connection of the injector is reinforced by o-rings on either side of the groove.